<!doctype html>
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Copyright 2018 The Immersive Web Community Group

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IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-->
<!--
This is a somewhat modified version of the xr-barebones page, which adds a
rotating color square to the DOM content as well as adding support to capture
and show the contents of the page via the WebRTC APIs.
-->
<html>
  <head>
    <meta charset='utf-8'>
    <meta name='viewport' content='width=device-width, initial-scale=1, user-scalable=no'>
    <meta name='mobile-web-app-capable' content='yes'>
    <meta name='apple-mobile-web-app-capable' content='yes'>

    <title>Tab Capture Test</title>
    <link href='../css/common.css' rel='stylesheet'></link>
    <style>
      #session-info {
          font-weight: bold;
          font-family: monospace;
      }

      /* Override the default canvas styling which would make the canvas full
         screen and on top of everything... */
      #colorsquare {
        position: relative;
        z-index: auto;
        width: 100px;
        height: 100px;
        left: auto;
        top: auto;
        right: auto;
        bottom: auto;
        margin: auto;
      }
    </style>
  </head>
  <body>
    <header>
      <details open>
        <summary>Tab Capture Test</summary>
        <p>
          This sample demonstrates a simple AR page which uses DOM Overlay to
          help show a capture of the current tab.
          <a class="back" href="./index.html">Back</a>
        </p>
        <div id="session-info"></div>
        <div id="warning-zone"></div>

        <button id="xr-button" class="barebones-button" disabled>XR not found</button>
        <button id="capture-button" class="barebones-button">Start Screen Capture</button>
        <video id="capture-video" autoplay playsinline muted height=100></video>

      </details>
    </header>
    <main style='text-align: center;'>
      <p>Click 'Enter AR' to see content</p>
      <canvas id="colorsquare"/>
    </main>
    <script type="module">
      // XR globals.
      const xrButton = document.getElementById('xr-button');
      let xrSession = null;
      let xrRefSpace = null;

      // getDisplayMedia globals.
      const captureButton = document.getElementById('capture-button');
      const video = document.getElementById('capture-video');
      let videoStream = null;

      // WebGL scene globals.
      let gl = null;

      function checkSupportedState() {
        navigator.xr.isSessionSupported('immersive-ar').then((supported) => {
          if (supported) {
            xrButton.innerHTML = 'Enter AR';
          } else {
            xrButton.innerHTML = 'AR not found';
          }

          xrButton.disabled = !supported;
        });
      }

      function initXR() {
        if (!window.isSecureContext) {
          document.getElementById("warning-zone").innerText =
              "WebXR unavailable due to insecure context";
        }

        if (navigator.xr) {
          xrButton.addEventListener('click', onXRButtonClicked);
          captureButton.addEventListener('click', oncaptureButtonClicked);
          navigator.xr.addEventListener('devicechange', checkSupportedState);
          checkSupportedState();
        } else {
          document.getElementById("warning-zone").innerText =
              "WebXR unavailable.";
        }
      }

      function oncaptureButtonClicked() {
        if (!videoStream) {
          navigator.mediaDevices.getDisplayMedia({video: true, preferCurrentTab: true})
            .then(onCaptureSuccess, onCaptureError);
        } else {
          // Before we stop the tracks we need to cleanup the state of anything
          // that might be using them; so we'll call onCaptureEnded. However,
          // this also clears the videoStream variable, so cache the tracks that
          // we need to stop ahead of time.
          const tracks = videoStream.getTracks();
          onCaptureEnded();
          tracks.forEach(track => track.stop());
        }
      }

      function onCaptureSuccess(stream) {
        videoStream = stream;
        video.srcObject = stream;
        videoStream.getVideoTracks()[0].addEventListener('ended', onCaptureEnded);
        captureButton.innerHTML = 'Stop Screen Capture';
      }

      function onCaptureEnded() {
        video.pause();
        video.srcObject = null;
        videoStream = null;
        captureButton.innerHTML = 'Start Screen Capture';
      }

      function onCaptureError(ex) {
        document.getElementById("warning-zone").innerText =
            "Failed to get display media.";
        console.error(ex.message);
      }

      function onXRButtonClicked() {
        if (!xrSession) {
            // Ask for an optional DOM Overlay, see https://immersive-web.github.io/dom-overlays/
            // Use BODY as the root element.
            navigator.xr.requestSession('immersive-ar', {
                optionalFeatures: ['dom-overlay'],
                domOverlay: {root: document.body}
            }).then(onSessionStarted, onRequestSessionError);
        } else {
          xrSession.end();
        }
      }

      function onSessionStarted(session) {
        xrSession = session;
        xrButton.innerHTML = 'Exit AR';

        // Show which type of DOM Overlay got enabled (if any)
        document.getElementById('session-info').innerHTML = 'DOM Overlay type: ' + session.domOverlayState.type;

        session.addEventListener('end', onSessionEnded);
        const canvas = document.createElement('canvas');
        gl = canvas.getContext('webgl', {
          xrCompatible: true
        });
        session.updateRenderState({ baseLayer: new XRWebGLLayer(session, gl) });
        session.requestReferenceSpace('local').then((refSpace) => {
          xrRefSpace = refSpace;
          session.requestAnimationFrame(onXRFrame);
        });
      }

      function onRequestSessionError(ex) {
        alert("Failed to start immersive AR session.");
        console.error(ex.message);
      }

      function onEndSession(session) {
        session.end();
      }

      function onSessionEnded(event) {
        xrSession = null;
        xrButton.innerHTML = 'Enter AR';
        document.getElementById('session-info').innerHTML = '';
        gl = null;
      }

      function onXRFrame(t, frame) {
        const session = frame.session;
        session.requestAnimationFrame(onXRFrame);
        const pose = frame.getViewerPose(xrRefSpace);

        if (pose) {
          gl.bindFramebuffer(gl.FRAMEBUFFER, session.renderState.baseLayer.framebuffer);

          // Update the clear color so that we can observe the color in the
          // headset changing over time. Use a scissor rectangle to keep the AR
          // scene visible.
          const width = session.renderState.baseLayer.framebufferWidth;
          const height = session.renderState.baseLayer.framebufferHeight;
          gl.enable(gl.SCISSOR_TEST);
          gl.scissor(width / 4, height / 4, width / 2, height / 2);
          const time = Date.now();
          gl.clearColor(Math.cos(time / 2000), Math.cos(time / 4000), Math.cos(time / 6000), 0.5);
          gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
        }
      }

      function initDOMColorSquare() {
        // Add a box to the DOM content that cycles colors so we can ensure that
        // the DOMOverlay is actually being live updated.
        const colorSquare = document.getElementById('colorsquare');
        const ctx = colorSquare.getContext('2d');

        function paintCanvas() {
          const time = Date.now();
          const r = (Math.abs(Math.cos(time/2000)) * 255);
          const g = (Math.abs(Math.cos(time/4000)) * 255);
          const b = (Math.abs(Math.cos(time/6000)) * 255);
          const color = "rgb("+r+","+g+","+b+")";

          ctx.fillStyle = color;
          ctx.fillRect(0,0, colorSquare.width, colorSquare.height);
        }

        window.setInterval(paintCanvas, 32);
      }

      initDOMColorSquare();
      initXR();
    </script>
  </body>
</html>
